The present invention relates to a device for testing the headlight orientation of a headlight of a motor vehicle, i.e. the direction in which a light beam produced by the headlights travels, and, more particularly, to a device for testing headlight orientation in the motor vehicle which is standing on an incline or slope.
A headlight aiming and leveling device is described in U.S. Pat. No. 4,802,067. This device has an inclination-detecting device in the form of a bubble level located in the headlights. The inclination-detecting device indicates the variation of the inclination of the headlight from a set value of headlight angular orientation. The light beam emitted by the headlight must often satisfies certain legal requirements regarding the beam direction. The bubble level has a high resolution allowing the exact adjustment of the inclination of the headlight. This means that the air bubble of the bubble level moves over a comparatively large path, when comparatively small inclination changes of the headlight occur. Only a comparatively small variation of angular inclinations of the headlight can be read off the bubble level. This small reading range can only be used, when the motor vehicle stands on an exact horizontal position, since otherwise the suitable angular position of the headlight relative to the road surface can not be determined.